Developments in communications in our increasingly mobile society has resulted in the introduction of mobile units that provide mobile communication and processing capabilities. A network of cellular telephone systems is a suitable conduit for communications with mobile units associated with people, vehicles, cargo containers, or other mobile items. However, the cost of using traditional cellular communication is prohibitive, both in terms of chargeable air time and roamer fees. This is especially true in applications such as nationwide trucking, where mobile units move through a number of cellular systems.
Existing systems require a failed attempt to the last known cellular system before attempting communication using other techniques. This often contributes to increased costs associated with failed communication attempts or delayed transmission of information to or from the mobile unit. Yet another problem with using a cellular network for communication with mobile units is that cellular systems may not realize that a mobile unit has powered down. Failed attempts to a powered down mobile unit often contribute to increased costs.